Dublin-based eurosceptic campaign group the National Platform says it is “seriously considering” seeking a High Court injunction to prevent Bertie Ahern’s administration from holding a second poll following the electorate’s rejection of the Treaty on 7 June. It will argue that any attempt by the government to call a second referendum will amount to “unconstitutional” behaviour.

The decision to mount a possible legal challenge follows a meeting between National Platform secretary Anthony Coughlan – one of the leaders of the No campaign – and European Commission President Romano Prodi last weekend.

Coughlan told European Voice that he had made it clear to Prodi that the No campaign, including the Green Party and Sinn Fein, would not give up their fight. “We’re not against EU enlargement; we’re against a two-tier Europe,” said Coughlan. “That’s what this Treaty will mean.”

The government, he said, had done an “an appalling disservice” to the electorate by going to the Göteborg summit and apologising for the outcome, and giving the impression that voters had been confused. “There is something quite wrong with governments forging ahead with treaties they know their people don’t want. The Irish people have voted and clearly they don’t want the Treaty. “Why should they have to vote again? In our opinion, the ratification process should stop right now.”It is our belief that in failing to abide by the result of the referendum on June 7 the Irish Government may have acted unconstitutionally. “We shall therefore ask our lawyers to look into the possibility of applying for an injunction. We feel very strongly on this matter and are prepared to go all the way to the Supreme Court if necessary.”

Coughlan said Prodi and the EU leadership were still “clearly rattled” by the outcome of the referendum. During his four-day visit to Ireland last week, Prodi made contradictory statements over the significance of the Irish vote. Initially, he said ratification was not necessary for enlargement to go ahead.

Within 24 hours he had back-tracked, saying it was a political necessity. He later attempted to clarify his position in an article for Italian newspaper Corriere della Sera, saying: “The real problem is a political one and, as a politician, I have to warn against the temptation of thinking enlargement can go ahead as planned if Nice fails. That would be a serious mistake. “To my Irish friends, I say: Look at Nice, think about the implications and when you are ready, we will be here to answer your concerns. “But remember that the decision, which only you can take, will have a decisive impact on the future of the whole continent.”

His diplomatic language, however, has done nothing to soften the attitude of National Platform. Coughlan says it has a number of serious backers, including lawyers willing to work for it on a pro bono or no-win, no-fee basis in any action.

They are expected to rely on a 1996 Irish Supreme Court ruling on the Hanafin case, which centred on the country’s divorce referendum. The government was then admonished for using public money to support one side of the campaign. However, the referendum result – narrowly in favour of allowing divorce – was allowed to stand.

Meanwhile, Coughlan is building support for a possible action against the government through his group’s website which is run by Oisín O’Connell, the son of a wealthy Bronx-born Irish-American, and supported by eurosceptic Danish website euobserver.com.